This invention relates to image forming methods and apparatus for a heat-developable image forming sheet which is deposited over its organic substrate with a heat-developable image forming layer that is rendered photosensitive by preheating prior to exposure and forms therein a latent image by exposure and then provides a visible image by heat development.
A heat-developable image forming sheet, which is rendered by preheating prior to exposure and exposed to form therein a latent image and then heated to obtain an image (which sheet will hereinafter be referred to simply as the image forming sheet), can provide thereon a visible image only by the dry process, and the image forming sheet is non-photosensitive before it is made photosensitive by preheating. Accordingly, when only a specified area of the image forming sheet is rendered photosensitive by preheating and exposed and then heat-developed, an image is formed only in the specified area, but the other areas which are not made photosensitive at first remain non-photosensitive. Consequently, the abovesaid image forming sheet permits additional recording of an image thereon by preheating and exposing a specified section of an unrecorded area and then heat-developing it.
To render such an image forming sheet photosensitive by preheating is referred to as heat activation, and to render a latent image into a visible image by heating is called heat development.
With a conventional image recording method involving the preheating-exposure-heat development process for the image forming sheet, difficulties are encountered in obtaining an image of good quality due to heat deformation of the image forming area by heating thereof for development.
If a high-grade image can be formed on a desired area of the image forming sheet in a short time, then it is possible to enhance superiority and usefulness of the image forming sheet permitting additional image recording and to provide convenient and useful recording means.
An object of this invention is to provide image forming methods and apparatus which permit the formation of a high-grade image in a short time.
As a result of intensive researches made with a view to achieving the above object, for improvement in the image forming method for the image forming sheet, the present inventors have found out that a high-grade image can be obtained by appropriate heating and cooling methods, and have now completed this invention.